River birch tree named ‘WHIT XXV’

ABSTRACT

A new and distinct cultivar of river birch tree,  Betula nigra,  named ‘WHIT XXV,’ characterized as having a tree form that is broadly pyramidal to oval and may be grown with a single stem or multiple stems for greater landscape appeal. The bark of the ‘WHIT XXV’ is creamy-white during the late summer, fall and winter, developing its coloration at a young age when most stems are about 0.75 to 1.0 inch in diameter. The leaves are dark green of moderate size and turn yellow-gold in the fall.

Genus and species: Betula nigra.

Varietal denomination: River Birch ‘WHIT XXV’.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new and distinct variety or cultivar of thedeciduous tree, Betula nigra, commonly known as river birch.

2. Description of the Related Art

River birch trees are native to stream banks and wet areas over much ofthe eastern half of the United States extending westward to central andnorthern Oklahoma. A river birch tree is typically about 30 to 60 feettall having a broad spreading crown and a short, thick, soon-branchingtrunk that is rarely larger than between about 12 and 24 inches indiameter. The bark is reddish brown or silvery gray, shiny and becomesfissured, separating into papery scales.

The inventor of this new and distinct river birch gathered a largequantity of seed from the western most native river birch seedlings incentral Oklahoma in 1986. but none of these gathered seeds germinated.In 1987, about three pounds of additional seeds were gathered from thewestern most native birch tree seedlings having the lightest bark incentral Oklahoma. These trees were located along a narrow steam that wastypically without flowing water for six months or more each year. Afterplanting, only a fraction of the seeds germinated and most of theseedlings were weak and did not survive the first summer. There were,however, three vigorous seedlings that survived and were planted into afield. Two of these seedlings were typical loose, open-branched treesand considered of little value.

The third seedling was more ornamental with denser branching, darkerleaves and slightly slower growth. In 1992, when the seedling was sixyears old, viable seeds were produced. The resulting seedlings fromthese produced seeds were planted in a field where they grew for fiveyears before producing viable seed. Seed was collected from one of theseseedlings having lighter bark than the others. Seedlings from this lastcollection of seeds were planted and allowed to grow.

The new plant of this invention was one of the seedlings grown from thelast collection of seeds and is distinctly different from its ancestors,the parent plant or its other siblings. The new plant is characterizedas having creamy-white bark during late summer, fall and winter. Thewhite bark develops at a young age, when most stems are about 0.75 to1.0 inch in diameter. The leaves are dark green of moderate size andturn yellow-gold in the fall. The color of the bark of a typical riverbirch tree is a cinnamon tan to light brown. While the bark of someriver birch trees develop a creamy tan color on larger stems, thepresent cultivar differs from other river birch trees known to theinventor as having bark that is creamy-white once the stems start topeel, even at a very young age when the stems have diameters of betweenabout 0.75 and 1 inch.

The river birch that is known to the inventor and appears to be the mostsimilar to that of the claimed river birch tree is the Dura-Heat® riverbirch tree. However, the Dura-Heat® river birch may be differentiatedfrom the current invention as having bark coloration under the peelingbark that is darker as well as rougher in texture. The rougher textureof the exposed bark under the peeling bark of the Dura-Heat® river birchtree is due to slender pieces of bark that are loose and thereby roughenthe bark surface.

This new and distinct plant was first asexually reproduced by rootingsoftwood cuttings from the original plant near Stillwater, Okla. Theasexually reproduced plants show the unique features that characterizethis new river birch tree indicating that the unique features of thisplant are stable through its successive generations of asexualreproduction.

SUMMARY OF THE INVENTION

The present invention resulted from the discovery of a new and distinctvariety of river birch tree, Betula nigra, which has been given thecultivar name ‘WHIT XXV.’ ‘WHIT XXV’ is characterized as having a treeform that is broadly pyramidal to oval and may be grown with a singlestem or multiple stems for greater landscape appeal. The bark of the‘WHIT XXV’ is creamy-white during the late summer, fall and winter,developing its coloration at a young age when most stems are about 0.75to 1.0 inch in diameter. The leaves are dark green of moderate size andturn yellow-gold in the fall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a full color photographic view of my new river birch tree.

FIG. 2 is a full color photographic view of the creamy-white bark on a1.5 inch diameter stem of the tree shown in FIG. 1.

FIG. 3 is a full color photographic view of young bark peeled away toexpose the creamy-white inner bark on a stem section measuring about0.75 inches in diameter at the top of the stem section and about 1.25inches in diameter at the bottom of the stem section on a typicalspecimen of my new river birch tree.

FIG. 4 is a full color photographic view of the bark peeled back on thebase stems of the tree shown in FIG. 1 to reveal the creamy-white innerbark.

FIG. 5 is a full color photographic view of the upper and lower surfacesof mature leaves on a typical specimen of my new river birch tree.

BOTANICAL DESCRIPTION OF THE PLANT

The following botanical description is of the new and distinct cultivarof the river birch tree, Betula nigra, named ‘WHIT XXV’. Specific colordesignations set forth by number designations are in accordance with TheRoyal Horticultural Society Colour Chart. General color recitations areconsistent with ordinary American color terminology.

The river birch tree ‘WHIT XXV’ has not been observed under all possibleenvironmental conditions. It is to be understood that the phenotype mayvary significantly with variations in environment such as soils,temperature, light intensity, and length of day, without any differencesin the genotype of the plant. The following botanical characteristicsand observations are taken from the plant when grown under normaloutdoor conditions in north central Oklahoma. The described plant wasabout 7 years old growing in a field in north central Oklahoma inSeptember.

-   The plant:    -   -   Type.—Woody tree with single or multiple stems.        -   Classification.—River birch tree, Betula nigra.        -   Growth habit.—Pyramidal when young, growing more oval with            age.        -   Origin.—An open pollinated cross in a birch            selection/breeding program in Stillwater, Okla.        -   Parentage.—The parent plant was a third generation seedling            from a native river birch tree growing in central Oklahoma.            The parent plant originated from seeds taken from seedlings            planted in 1992, which originated from seedlings planted in            1987, which originated from seeds collected from the native            river birch trees in central Oklahoma. The seeds were            gathered selectively from each generation of trees having            the whiter bark. The parent plant resulted from these            repeated selections of seeds from trees with whiter bark.            The parent plant was an unnamed river birch tree that is            still growing in a field of trees in north central Oklahoma.        -   Propagation.—The plant is easy to propagate from softwood            cuttings taken in May, June or July in north central            Oklahoma, with the distinguishing characteristics disclosed            herein being firmly fixed and retained through the            successive generations of asexual reproduction.        -   Size and shape.—The growth habit is a treeform that is broad            oval. The tree may be grown with either a single stem or, to            provide a more ornamental look, may be grown with multiple            stems that are created by timely pruning. The growth rate is            vigorous in late spring and early summer and continues into            midsummer when moisture is adequate. Branches are produced            in abundance and are typically removed from the lower            portion of the stem(s) to expose the creamy white bark. In            north central Oklahoma, the plant size is characterized as            having a height of between about 30 and about 50 feet. The            specimen shown in FIG. 1 is approximately 14 feet tall with            spread of about 10.5 feet. The broad oval growth habit is            not observable in FIG. 1 as the lower limbs have been            removed. The four major stems of the illustrated specimen            range between about 1.5 and 3 inches.        -   Hardiness.—USDA hardiness zones 5 through 9.        -   General health and pest susceptibility.—The foliage of the            river birch ‘WHIT XXV’ has remained pest free in central            Oklahoma. The plant is characterized as being resistant to            bronze birch borer and leaf-spot disease.-   Foliage:    -   -   Leaf persistence.—Deciduous.        -   Arrangement on stems.—Alternate.        -   Shape of leaves.—As shown in FIG. 5, the leaves are oval,            short-pointed, and slightly wedge shaped at the base.            Typically, the leaves have 7 to 9 main veins on each side of            the midrib.        -   Size of leaves.—Typically, the leaves are between about 1.5            and about 3.0 inches long and between about 1.0 and 2.0            inches wide.        -   Margins of leaves.—Dentate, each dentate showing between            about 2 and about 5 smaller serrations.        -   Quantity.—Singles that alternate on the twig.        -   Color of leaves.—During the growing season, the upper leaf            surface is a shiny green (147-B or C) on young leaves and a            darker green (147-A) on fully expanded leaves. The lower            leaf surface is yellow-green (148-B or C) on young leaves            and grey-green (191-A or B) on fully expanded leaves, with            the midveins being grayish (160-A). The fall color of the            leaves is yellow-gold (22-A or B).        -   Surface texture of leaves.—The upper leaf surface has a            slightly rough texture that feels thick and tough. The under            leaf surface has a softer texture due to pubescence            distribution.        -   Leaf petiole.—The leaf petiole is between about 0.3 and            about 0.6 inches long. The surface texture of the leaf            petiole is similar to that of the underside of the leaf in            that it is pubescent, which gives it the grayish (160-A)            color.        -   Stipules.—None.        -   Stems.—The numerous stems are characterized as being            slender, spreading and flexible.        -   Stem color and texture.—Young stems having a diameter less            than between about 0.75 inches and 1 inch are shiny, smooth            and orangey-brown (177-A or B or 200-C or D) with prominent            lenticles. The number and color of lenticles is extremely            variable and not different than other known cultivars of            river birch trees. The color designations of the lenticles            are most often in the 156-A, B, or C range but are quite            variable. Stems having a diameter of between about 0.75            inches and about 1 inch and larger, typically near the end            of the second growing season, have a peeling bark. The            peeling bark pieces on young stems are dark tan (166-A or            B). By late September, in central Oklahoma, the exposed bark            on stems having diameters of between about 0.75 and about            one inch or larger is creamy-white (158-C or D) and smoother            than the bark found on some other river birch trees, such as            the Dura-Heat® river birch tree. The bark coloration remains            this color until active growth is well under way the            following April or May, when the exposed bark begins to            darken. For example, the old bark on the tree shown in FIG.            1 had darkened to a cream color (159-A or B).-   Flowers: Male and female flowers appear in separate catkins on the    same tree. The male flowers are characterized as hanging clusters of    slender, shiny dark brown (166-A or B) catkins that are between    about 1.5 inches and about 2.5 inches long. The female flowers are    characterized as being in upright green (147-A or B) catkins that    are between about 0.15 and about 0.4 inches long.

The male flowers typically appear in early to mid-April in Stillwater,Okla. and seeds reach maturity by early to late May. Female flowersappear in late April to early May. The dormant winter buds are typicalof those found on other river birch trees.

-   Fruits: The fruits are cylinder shaped, hanging cones with tan    coloring (166-A, B or C) and are between about 0.75 and about 1.5    inches long. The fruits are composed of numerous three-lobed scales,    each scale enclosing a single, tiny winged seed.

1. A new and distinct variety of a river birch tree, substantially asillustrated and described.